The Grand Old Duke of York
The grand old Duke of York,
He had ten thousand men.
He marched them up to the top of the hill
And he marched them down again.
And when they were up, they were up;
And when they were down, they were down.
But when they were only halfway up,
They were neither up nor down!
Now applying this to Darwin’s Finches:
The Grand Old El Nino
The grand old El Nino
He drove ten thousand birds
He drove them out into a drought
And he drove them back again.
When those beaks are dry they’re thick
And when they’re wet their thin
And when they’re only half way dry
They’re neither thick nor thin.
This distribution in beak size and consequent cyclic variation with El Ninos can be predicted by the following design principle:
Provide variety and robustness.
Form distributions of genes (alleles) that give variations in beak size.